clojure.core/take-nth

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Type: function Added: Clojure 1.0 Examples: 2 Runnable: 2

([n] [n coll])

Returns a lazy seq of every nth item in coll. Returns a stateful transducer when no collection is provided.

Examples

by devn on 2010-08-02 ▶

(take-nth 2 (range 10)) (0 2 4 6 8)

by miner on 2015-05-21 ▶

;; N <= 0 is a special case (take 3 (take-nth 0 (range 2))) ;;=> (0 0 0) (take 3 (take-nth -10 (range 2))) ;;=> (0 0 0)

Note by Dimagog

(take-nth 0 (range 10)) will loop forever.

Note by miner

(take-nth 0 coll) will return an infinite sequence repeating for first item from coll. A negative N is treated the same as 0.

Note by reborg

;; In case you are searching for it, drop-nth is not in core.

(defn drop-nth [n coll]
  (lazy-seq
    (when-let [s (seq coll)]
      (concat (take (dec n) (rest s))
              (drop-nth n (drop n s))))))

(drop-nth 3 (range 10))
;; (1 2 4 5 7 8)

;; or alternatively: (keep-indexed #(when-not (zero? (rem %1 n)) %2) coll)

See also

• clojure.core/partition (6)
• clojure.core/nth (1)
• clojure.core/rand-nth (0)

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